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Thanks for all the advise. I did cut out all the low spots and blew a rag- plug thru the line set. Started one side of one unit today and low and behold no problems. Will be hopefully start other circuits tommorow. I pulled a deep vac 4 times and introduced 410 each time to grab any moisture. Oil at compressers looks good and I am getting 40 degrees at evap coil.

Allstar08,
What were the problems you that you were having and how many times did you change the oil
I noticed after the first day we had to drain some of the oil because the compressors were getting to full

Allstar08,
What were the problems you that you were having and how many times did you change the oil
I noticed after the first day we had to drain some of the oil because the compressors were getting to full

im not the OP ....but I had a run in with mixed oil....

I had a factory ordered water cooled (condensor ,air over evap) split that was built to run on R134A and carrier filled the comps with mineral oil .... I spent a couple days and if I remember went thru 20 gallons (for two 06E's) of oil before I was under 5% mineral to poe ....
im thinking around 5 changes per compressor ....
134 because it was a refrigerator factory and they wanted a cooling system for their offices that ran on 134A,just like their product

my experience was the mineral tended to lay out in the system and as you got more poe in it all started coming back at a rate that I had to babysit it .... at first the oil just left and did not come back . I had a gut feeling before I started it that it was wrong but was shown it was ordered for 134A service . My gut was right.
.

Without an oil refrac I would have been guessing ....that unit has been running close to ten years now with no compressor failures....

Thanks for the info
I flushed the holy crap out of the system but there is no way to get all the mineral oil out
I hope the compressor collects most of it and it doesn't take to many changes
I get the two oils don't mix but I wouldn't think it would damage the compressors to bad scrolls are fairly forgiving ( I pray )

i know that you are just asking about oil changes, but you did change out the compressors too...right? txv's? you might consider running for the border when this is done. change your phone number. change the company name. mother nature doesn't care if your budget can't handle it. r22 and r410a are 2 very different refrigerants and they require the proper engineering and design to make them work. you will probably be changing out the evaporators before too long.

not that it has to do with your original question, but why did the old compressors not last long? if it wasn't corrected, then, you should know that the new compressors are more expensive to replace than the old compressors were.

Yes I changed out all the goodies and rerouted the line set to get rid of the traps and low spots
Trane confirmed that the existing coil could handle 410
The existing unit killed quite a few compressors and it looks like it was because the way it was set up it kept lugging the compressors with oil
I'm not using the hot gas bypas but frost stats instead and so far were not slugging